Saklıkent is Turkey's longest gorge — an 18 km slot canyon cut through limestone by the Eşen river, with walls rising 300 metres on either side. You enter via a wooden walkway bolted to the canyon wall, then wade into the river itself. The water is cold — it is snowmelt from the Akdağlar mountains — and the current is surprisingly strong in places.
Most visitors go as far as the mud baths about 4 km in, where you can smear yourself with mineral-rich clay. Guides are available for longer treks deeper into the canyon. The gorge is about 45 km east of Fethiye and most tour operators offer half-day trips that combine it with a visit to the ancient city of Tlos. There are riverside restaurants at the entrance where you eat on platforms suspended over the water — a good spot for trout and gözleme.